Humoral immune response to inner ear proteins in patients with sensorineural hearing loss.

Background: The precise mechanism of inner ear disease is still unknown. An autoimmune reaction could be one of several possible pathogenic factors in volved in progressive sensorineural hearing loss. Heat shock protein 70 is suggested to play an important role in the development of autoimmune diseas es. The aim of this study is the investigation of humoral immune reactivity to inner ear components in patients with sensorineural hearing loss. Metho ds: The presence of antibodies to inner ear components was determined by im mune-blotting extracted bovine or human inner ear proteins. Study groups co nsisted of patients with idiopathic progressive sensorineural hearing loss (group A), patients with Meniere's disease (group B), patients with sudden hearing loss (group C), patients with otosclerosis (group D), patients with Cogan's disease (group E), and individuals without hearing problems (group F). Results: 40% of the patients with progressive sensorineural hearing lo ss showed reactivity against a 68-kDa protein extracted from bovine inner e ar. In contrast to this, only 5% of healthy individuals and 10% with Menier e's disease showed reactivity against the 68-kDa protein from bovine inner ear or against bovine heat shock protein 70. Some of the patients who showe d reactivity against bovine inner ear proteins were tested with human inner ear and human heat shock protein 70; all of these showed reactivity. Appro ximately 6% of the patients with sudden hearing loss (group C), otosclerosi s (group D), and Cogan's disease (group E) showed reactivity to inner ear p roteins. A non-specific humoral immune reaction against inner ear proteins with molecular weights of 30, 40, 50, 60, and 220 kDa was observed in all p atients. Discussion: These results indicate a humoral immune reactivity aga inst heat shock protein 70, which might be responsible for the pathogenesis of progressive sensorineural hearing loss.